Mitsubishi Reports Overheated Battery in Outlander Plug-in Hybrid

Mitsubishi Motors yesterday asked customers not to charge the plug-in hybrid Outlander Plug-in Hybrid after a lithium-ion battery overheated last week, melting the cell and part of the battery pack. In a separate incident, a battery caught fire while being tested at a company factory.

The batteries involved in the incidents were made by Lithium Energy Japan, a venture between GS Yuasa, Mitsubishi Motors and Mitsubishi Corp. Company investigators are working to identify the cause of the problem.

Mitsubishi said the overheating incident in the Outlander Plug-in Hybrid occurred when staff tried to move the vehicle before shipment, according to the Wall Street Journal.

Even though no injuries have been reported, and the cause of the incidents is unknown, reports of potential safety issues raise concerns among all EV stakeholders—including drivers, carmakers and suppliers. Most observers point to relatively high cost and limited driving range as primary market obstacles to plug-in cars. Doubts about safety, even if minor and unfounded, could potentially be amplified by electric vehicle detractors—causing negative impacts on public perception about electric cars.

Mitsubishi has suspended shipments of the Outlander PHEV, according to the Wall Street Journal. Mitsubishi has so far shipped about 4,000 units of the Outlander PHEV; 68 i-MiEV vehicles fitted with the batteries; as well as enough spare batteries for use in 45 vehicles since recent production line changes were made that could be related to the incidents.

In early February, Mitsubishi Motors U.K. officially launched the gas-powered version of the new Outlander crossover SUV, promising that the forthcoming plug-in hybrid version will arrive in the U.K. by June. The Outlander PHEV is the first four-wheel-drive seven-seat plug-in hybrid. It’s expected to go on sale in the United States in 2014. The model is capable of about 30 miles of all-electric range, and another 250 or so miles using internal combustion. It can travel at speeds up to about 75 miles per hour strictly using electric propulsion.

Impact Unknown

GS Yuasa Corporation also made the ill-fated lithium-ion batteries that caught fire in a Boeing 787 Dreamliner in January.

As PlugInCars.com reported a year ago, GS Yuasa is ramping up production as one of Honda’s key lithium-ion battery suppliers to supply 15 million cells annually (triple Honda’s previous capacity). It is uncertain how the overheating problems reported by Mitsubishi will affect production timelines.

Yuuji Fujiki, chief engineer for Honda’a IMA hybrid system, said in 2011 that its lithium ion batteries are “very safe” and operate at relatively low temperatures. Even if a needle is stuck into the battery, he said, “a fire is not going to break out.” Company spokesman Chris Naughton told PlugInCars.com, "Our battery is completely different, and not based on the battery [in the Boeing planes]. We have subjected our battery to rigorous testing (including extensive crash testing and piercing it with a long metal rod) to ensure it remains safe and stable."

Kumiko Hashimoto, a spokeswoman for Honda, told Bloomberg that it has not received any reports of accidents with the batteries.

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